1. Field of the Invention
The present invention relates to a derailment detecting method and derailment detecting apparatus for automatically detecting derailment of rolling stock.
2. Related Background Art
In general, in the event of derailment of rolling stock, the derailment must be detected by the motorman etc. of the rolling stock, by visual recognition or personal sensation of the motorman etc. However, in the case that the derailment should occur at a car coupled in the rear, even during manned operation, there would be possibilities that the motorman etc. could fail to recognize the derailment. For automatic unmanned operation of rolling stock, it is necessary to prevent the derailed rolling stock from keeping running and stop the rolling stock immediately upon occurrence of the derailment.
An object of the present invention is, therefore, to provide a derailment detecting method and derailment detecting apparatus for rolling stock capable of automatically detecting the derailment of rolling stock.
A derailment detecting method for rolling stock according to the present invention is applied to the rolling stock comprises a truck having wheels rolling on rails and spring rigging, and a carbody to which the truck is attached. In this derailment detecting method, the rolling stock is preliminarily made to travel at varying running velocities on a predetermined route. On that occasion, a maximum of vertical acceleration at the carbody above the spring rigging is measured in a predetermined frequency range and at each of the varying running velocities. Then, from each maximum of vertical acceleration, a limit vertical acceleration is defined as a threshold for detecting the derailment at each running velocity. During actual traveling of the rolling stock on the route, real running velocity of the rolling stock is detected. During the actual traveling, real vertical acceleration is also detected at the carbody above the spring rigging. A component in the above-stated frequency range is extracted from the real vertical acceleration detected. In the case that an absolute value of the real vertical acceleration in the frequency range exceeds the limit vertical acceleration corresponding to the real running velocity detected, it is then determined that the rolling stock is derailed.
As described above, the limit vertical acceleration is defined to be in correspondence to each real running velocity of the rolling stock. Then, during the actual traveling of the rolling stock, the vertical acceleration at the carbody etc. is compared with the limit vertical acceleration corresponding to the real running velocity. As a result, the derailment can be detected accurately and surely.
In this case, it is preferable to set the limit vertical acceleration to a value larger than the maximum of the vertical acceleration previously measured.
It is also preferable to determine that the rolling stock is derailed, in the case that there occur a predetermined number of such events that the absolute value of the real vertical acceleration exceeds the critical vertical acceleration corresponding to the real running velocity within a predetermined time period. As a result, it is possible to avoid an accident of erroneously detecting the derailment because of enormous vertical acceleration exceptionally appearing during normal traveling.
Further, it is preferable that the aforementioned frequency range be a frequency range in which an absolute value of permissible vertical acceleration for assuring riding comfort is set at a minimum. Since in such a frequency range the difference becomes definite between vertical acceleration during normal traveling and vertical acceleration at derailment, the derailment can be detected accurately and surely.
Another derailment detecting method for rolling stock according to the present invention is applied to the rolling stock comprises a truck having wheels rolling on rails and spring rigging, and a carbody to which the truck is attached. In this derailment detecting method, the vertical acceleration is detected at the carbody above the spring rigging during running of the rolling stock on the rails. Then a vertical displacement amount is calculated by double integral of the vertical acceleration every predetermined evaluating time. This yields an amount of vertical displacement per evaluating time of the part above the spring rigging. In the event of the derailment of the rolling stock, the part above the spring rigging would descend over a predetermined amount. It is thus determined that the rolling stock is derailed, in the case that the vertical displacement amount is negative and an absolute value thereof is not less than a predetermined reference value. Employed as the evaluating time is a time period between a start of descent of the carbody and arrival at half the height of the rails, in a free fall of one axle of the wheels by a distance equal to the height of the rails. As a result, it is possible to surely discriminate between steady-state vertical displacement amounts of the carbody etc. during the normal traveling and vertical displacement amounts of the carbody etc. in the event of the derailment, both in flat territory and in gradient territory.
In this case, it is preferable on the occasion of the calculation of the vertical displacement amount to execute the double integral with the initial velocity of zero. This can cancel out the steady-state vertical displacement amounts of the carbody etc. under high-speed running in the gradient territory, whereby the derailment can be detected accurately and surely.
It is also preferable that the reference value for the comparison with the vertical displacement amount resulting from the double integral of the vertical acceleration be set to a value larger than a maximum change amount in the vertical direction of the spring rigging. In general, the height of rails is greater than the maximum change amount in the vertical direction of the spring rigging during the normal traveling of rolling stock. Therefore, at the event of the derailment of tolling stock, the carbody etc. would descend by an amount exceeding the maximum change amount in the vertical direction of the spring rigging during the normal traveling. Therefore, the derailment can be detected accurately and surely by setting the reference value for the comparison with the vertical displacement amount as described above.
A derailment detecting apparatus for rolling stock according to the present invention is applied to the rolling stock comprises a truck having wheels rolling on rails and spring rigging, and a carbody to which the truck is attached. This derailment detecting apparatus comprises a limit acceleration storage, a car velocity detector, an acceleration storage, a filter, and a determining part. The limit acceleration storage stores limit vertical acceleration as a threshold for detecting derailment. The limit vertical acceleration is defined for each running velocity from a maximum of vertical acceleration in a predetermined frequency range. Each running velocity is detected at the carbody above the spring rigging, at each of varying running velocities during traveling of the rolling stock at the varying running velocities on a predetermined route. The car velocity detector detects the real running velocity of the rolling stock traveling on the route. The acceleration detector detects the real vertical acceleration at the carbody above the spring rigging during traveling of the rolling stock on the route. The filter extracts a component in the above frequency range from the real vertical acceleration. Then the determining part determines that the rolling stock is derailed, in the case that an absolute value of the real vertical acceleration in the mentioned frequency range exceeds the limit vertical acceleration corresponding to the real running velocity.
Another derailment detecting apparatus of rolling stock according to the present invention is applied to the rolling stock comprises a truck having wheels rolling on rails and spring rigging, and a carbody to which the truck is attached. This derailment detecting apparatus comprises an acceleration detector, an integrator, and a determining part. The acceleration detector detects the vertical acceleration at the carbody above the spring rigging during running of the rolling stock on the rails. The integrator calculates a vertical displacement amount by double integral of the vertical acceleration every evaluating time. The evaluating time is a time period between a start of descent of the carbody and arrival at half the height of the rails, in a free fall of one axle of the wheels by a distance equal to the height of the rails. Then the determining part determines that the rolling stock is derailed, in the case that the vertical displacement amount is negative and an absolute value thereof is not less than a predetermined reference value.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.